TL;DR: The default Fedora cadence for updates in the RPM streams is once a day. Until now, the OSTree-based updates cadence has matched this, but we’re changing the default OSTree update stream to match the Fedora Atomic Host image release cadence (once every two weeks).

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In Fedora we release a new Atomic Host approximately every two weeks. In the past this has meant that we bless and ship new ISO, QCOW, and Vagrant images that can then be used to install and or start a new Atomic Host server. But what if you already have an Atomic Host server up and running?

Servers that are already running are configured to get their updates directly from the OSTree repo that is sitting on Fedora Infrastructure servers. The client will ask What is the newest commit for my branch/ref? and the server will kindly reply with the most recent commit. If the client is at an older version then it will start to pull the newer commit and will apply the update.

This is exactly how the client is supposed to behave, but one problem with the way we have been doing things in the past is that we have been updating everyone’s branch/ref every night when we do our updates runs in Fedora.

This has the side effect of meaning that users can get content as soon as it has been created, but it also means that the two week release process where we perform testing and validation really means nothing for these users, as they will get something before we ever did testing on it.

We have decided to slow down the cadence of the fedora-atomic/25/x86_64/docker-host ref within the OSTree repo to match the exact releases that we do for the two week release process. Users will be able to track this ref like they always have, but it will only update when we do a release, approximately every two weeks.

We have also decided to create a new ref that will get updated every night, so that we can still do our testing. This ref will be called fedora-atomic/25/x86_64/updates/docker-host. If you want to keep following the content as soon as it is created you can rebase to this branch/ref at any time using:

# rpm-ostree rebase fedora-atomic/25/x86_64/updates/docker-host

As an example, let’s say that we have a Fedora Atomic host which is on the default ref. That ostree will now be updated every two weeks, and only every two weeks: